On my last two clips I inserted a video transition and I received a message saying not suffiecnt space frames will be repeated. So I separated the clip with small gap and inserted a transition in the gap. I hope this is causing the issue. Thank you I will try to export it again.

Most likely that it is then. You need to trim the end of first clip and beginning of next clip, then butt them together, so there is "overlap", or extra frames available for the transition between the clips. One way to do this is to put the mouse pointer on the end of the clip and then press CTRL key, bracket will change then you can trim end of clip with a Ripple Edit (everything after moves as you adjust). Quucikly trim ins and outs this way so you can add transition